City planners are currently seeking to transform their cities into Smart Sustainable Cities (SSC) aiming to face the rapid urbanization and its related challenges. This transformation is often represented by a roadmap. Different approaches were introduced in the literature to assist in developing such a roadmap. However; a thorough analysis of these approaches shows none of them cover holistically all aspect of the SSCs. For instance, some roadmaps neglect analyzing the current challenges of a city. Others falls short in addressing one or more of the SSC six dimensions. None considers checking the city readiness for change. This constitutes a gap in knowledge that this research highlights and addresses through a sound theoretical foundation, specifically, by linking the Theory of Change to the SSC concept and introducing a theoretical logic model for the transformation towards SSCs. The latter is used to propose a coherent, systematic transformation roadmap that captures the cross-cutting readiness of a city along its infrastructures. It aims at assisting city planners, decision makers, and key stakeholders in understanding the essential aspects to be considered during their cities transformation journey. This research also summarizes the results of an undertaken validation process, confirming the components of the proposed roadmap.